This invention relates to a reception diversity control method and a diversity receiver, and more particularly to, a reception diversity control method and a diversity receiver that are designed to reduce the consumed power.
Various diversity circuits to obtain the stable reception quality even in case of fading are provided for receivers in mobile communication system, such as a cellular phone.
Diversity receivers with such a diversity circuit use various access systems according to the modulation system. For example, in the TDMA (time division multiple access) system that divides the transmit/receive timing regarding time, at an available slot timing, reception antennas are switched sequentially to search for a best-condition diversity route. At a reception timing just after that, the reception is conducted using this route.
Also, in the FDMA (frequency division multiple access) and CDMA (code division multiple access) systems that conduct the transmission/reception continuously regarding time and there is no time to switch the reception antennas, the post-detection diversity system is used.
FIG. 1 shows the ideas of TDMA, FDMA and CDMA.
The diversity system gives a large improvement effect to reception quality when a fading occurs on the radio-wave propagation path, but it needs much consumed power since multiple diversity circuits are operated simultaneously. Especially, in the latter post-detection diversity system, multiple series of reception circuits extending from the early-reception-stage low-noise amplification circuit to the detection circuit are necessary to drive, therefore the consumed power must increase.
Also, since in recent years cellular phones are required to be miniaturized, a big capacity of battery cannot be used. So, if the consumed power is much, then the duration time of battery must be shortened. This deteriorates the characteristic of cellular phone.
Japanese patent application laid-open No. 6-224804(1994) discloses a diversity receiver that is designed to reduce the consumed power to solve the problem above. This diversity receiver is allowed to stop the power supply to the receiver circuit for diversity when all of conditions (1) to (3) below are satisfied.
(1) the average of reception field level is higher than a given threshold.
(2)the fading frequency is lower than a predetermined frequency.
(3)the reception field level is not lowered a predetermined value from a previously measured value.
However, when calling from a car moving in a weak electric field, it is highly probable that this diversity receiver deviates from any one of the conditions (1) to (3). Therefore, the reduction of consumed power is not expectable.
Thus, in the conventional diversity receiver where the power supply to the receiver circuit for diversity is stopped only under the good reception conditions, there is the problem that the consumed power cannot be suppressed under the bad reception conditions.
Accordingly, it is an object of the invention to provide a reception diversity control method that the consumed power can are reduced even under the bad reception conditions.
It is a further object of the invention to provide a diversity receiver that the consumed power can be reduced even under the bad reception conditions.
According to the invention, a reception diversity control method for receiving and demodulating receive signal by multiple receiver circuits, selecting demodulated data received by a receiver circuit in the best reception state from digital demodulated data obtained, comprises the steps of:
taking out voice existence information included in the demodulated data selected; and
turning on the power sources of all the multiple receiver circuits when the voice existence information indicates that voice information exists, or turning off the power sources of the multiple receiver circuits except a predetermined receiver circuit of the multiple receiver circuits when the voice existence information indicates that no voice information exists.
According to another aspect of the invention, a reception diversity control method for receiving and demodulating receive signal by multiple receiver circuits, selecting demodulated data received by a receiver circuit in the best reception state from digital demodulated data obtained, comprises the steps of:
taking out voice amplitude information when conducting the signal processing of the demodulated data selected;
determining whether the amplitude information is higher than predetermined threshold level or not; and
turning on the power sources of all the multiple receiver circuits when the amplitude information is higher than the predetermined threshold level, or turning off the power sources of the multiple receiver circuits except a predetermined receiver circuit of the multiple receiver circuits when the amplitude information is lower than the predetermined threshold level.
According to another aspect of the invention, a reception diversity control method for receiving and demodulating receive signal by multiple receiver circuits, selecting demodulated data received by a receiver circuit in the best reception state from digital demodulated data obtained, comprises the steps of:
conducting the D/A conversion of the digital demodulated data to generate analogue voice signal;
measuring the amplitude value of the analogue voice signal;
determining whether the measured amplitude value is higher than a predetermined threshold level or not; and
turning on the power sources of all the multiple receiver circuits when the measured amplitude value is higher than the predetermined threshold level, or turning off the power sources of the multiple receiver circuits except a predetermined receiver circuit of the multiple receiver circuits when the measured amplitude value is lower than the predetermined threshold level.
According to another aspect of the invention, a reception diversity control method for receiving and demodulating receive signal by multiple receiver circuits, selecting voice signal received by a receiver circuit in the best reception state from analogue voice signals obtained, comprises the steps of:
measuring the amplitude value of the analogue voice signal;
determining whether the measured amplitude value is higher than a predetermined threshold level or not; and
turning on the power sources of all the multiple receiver circuits when the measured amplitude value is higher than the predetermined threshold level, or turning off the power sources of the multiple receiver circuits except a predetermined receiver circuit of the multiple receiver circuits when the measured amplitude value is lower than the predetermined threshold level.
According to another aspect of the invention, a diversity receiver, comprises:
a plurality of receiving antennas;
a plurality of receiver circuits that are provided corresponding to the plurality of receiving antennas and demodulate radio-frequency signal input through the plurality of receiving antennas;
a determination circuit that determines a receiver circuit to be estimated to be in optimum reception state from the plurality of receiver circuits;
a selection circuit that outputs selecting only demodulated data from the receiver circuit in optimum reception state determined by the determination circuit;
a digital signal processor that conducts the signal processing for voice reproduction to the demodulated data selected by the selection circuit;
a decoder circuit that outputs decoding signal processed by the digital signal processor into voice signal;
an information existence determination circuit that takes out voice amplitude information from the digital signal processor, determines that information exists when the amplitude information is higher than a predetermined threshold level, and determines that no information exists when the amplitude information is lower than the predetermined threshold level,
a plurality of power sources for receiver circuit that are provided corresponding to the plurality of receiver circuits and are allowed to turn on/off separately power sources supplied to the plurality of receiver circuits; and
a power supply circuit controlling circuit that controls the plurality of power sources for receiver circuit to supply power to all the plurality of receiver circuits when the information existence determination circuit determines that information exists, or controls the plurality of power sources for receiver circuit to supply power to only predetermined one of the plurality of receiver circuits when the information existence determination circuit determines that no information exists.